They do have steering issues on ice. Most vehicles do.
I had always considered using studded on the front, to balance the front/rear traction, during the winter.
You had some good reasoning for the body lift. Not just for looks or clearance.
As for the stiffening idea of the body lift, and a place to mount some side protection: Go find a convertible bug, and look at the reinforcement tubes running under the edges of the floor pan. They did this to add strength, when the roof was removed. It also makes a great place to attach rock sliders.
If you need more cargo area for the light stuff, you could use a longer roof basket, such as a Rolla (with the extension), and just add the necessary supports at the rear of the basket. This way you could still see out the rear window.
Or maybe something like this: from The Samba . com
You have a fun project, and some good ideas.